Bill Mumy was the original choice for Eddie Munster, but his parents didn't approve of the extensive makeup that would be used for his character. He would eventually guest on The Munsters: Come Back, Little Googie (1965), playing an incorrigible brat, during the first season.
Initially, Fred Gwynne did his own stunt work on the Munsters however, after falling flat on his back (which was the plan) and dismantling his head set, the studio hired Bill Foster(also known as Jeff County) as stunt double for Fred Gwynne. Fred Gwynne and Bill Foster met at Universal Studios when Bill (a security guard for Universal and an accomplished musician) saw Fred attempting to play a guitar one day and offered a few lessons.
For the first 13 episodes, in which Beverley Owen played Marilyn, Fred Gwynne appeared last in the opening credits. When Owen was replaced by Pat Priest and the sequence had to be re-shot, Gwynne appeared first in the credits. Since there were no further cast changes for the second season, the credits remained in that order for the remainder of the series.
This show and its "rival" series The Addams Family (1964) both debuted within a week of one another in September 1964. At the end of that year's TV season, this show ranked #18 in the Nielsens, with a rating of 24.7, while The Addams Family came in at #23, with a 23.9 rating. At the time, Nielsens indicated what percentage of American TV households tuned in to any given program. By the end of the following year, both series were cancelled.
The first season opening credits were an outrageous parody of the opening credits of The Donna Reed Show (1958), which always began with Donna Reed lovingly passing out lunches to her departing family members as they left the house one by one. Yvonne De Carlo, as Lily Munster, did the same thing.
Beverley Owen, who played Marilyn Munster in the first 13 episodes, is a natural brunette. She wore a wig, and her hairline was often covered up by a headband. Pat Priest, who played Marilyn for the remainder of the series, is a natural blond, so that is her natural hair.
After the pilot was filmed, CBS execs insisted on re-casting the role of Lily Munster. Initially, both Fred Gwynne and Al Lewis balked at the notion of the part going to Yvonne De Carlo. However, later both Gwynne and Lewis agreed De Carlo was a great comedic actress.
Although Bud Westmore is credited as make up artist on each installment of The Munsters, he merely supervised Universal's makeup department at the time. The actual, uncredited work was done by Karl Silvera (Herman's make-up and appliances) Perc Westmore (Grandpa), Abe Haberman (Lily) and 'Mike Westmore (I)' (Marilyn and Eddie).